Recently increasing attention has focused on the search of new polymerization initiators, in particular of fluorinated olefins. Among such initiators the perfluoroalkyl radicals proved to be particularly interesting. At present, however, the generators of perfluoroalkyl radicals are often too stable, such as, for instance CF.sub.3 I and azomethane hexafluoride, which need too high working temperatures in polymerization. See for instance: Rossi and Golden Int. J. Chem. Kinetics 1979, page 775, Okafo and Whittle, Int. Journal of Chem. Kinetics, page 287 (1975) and W. A. Sheppard C. M. Sharts "Organic fluorine Chemistry" page 89 (1969).
It is also common knowledge that use may be made of perfluoroacylperoxides, which present some advantages in comparison with the above mentioned initiators; they are, however, expensive and cannot be prepared easily, moreover they may be hydrolyzed with ease. Their application on industrial scale proves to be limited.
Therefore in industrial processes use is made of non-fluorinated initiators, such as persulfates in the dispersion polymerization of fluorinated monomers, for instance of C.sub.2 F.sub.4 or C.sub.2 F.sub.4 /C.sub.3 F.sub.6. In that case, reactive terminals are introduced, which decrease polymer characteristics, and therefore expensive treatments of the polymer are required, in order to convert the terminal groups into non-reactive groups (D. I. Mc. Cane Encyclopedia of Polymer Science and Technology vol. 13 pages 623-670).
In European Patent 121,898 a perfluoroalkyl radical was synthetized and isolated, which was stable at room temperature and was proposed as a polymerization initiator.
This product, however, is obtained with low yields and because the product is a perfluoroalkyl radical, it requires some precautions as regards storage and treatment, in order to avoid its decomposition. Moreover the radical obtained according to this process, cannot easily be separated from the reaction raw product. This separation is generally necessary, owing to the presence of perfluoroolefines together with the perfluoroalkyl radical, as these perfluoroolefins may interfere with the polymerization monomers.